I borrowed my sister in law's one she got on special offer at some fair! If I had £20 I would buy one.
Hers is the blonde colour, it's still quite dark, but I'm a dark blonde so it suits me. It comes out quite thickly on the applicator, like a gel. You think- this will look terrible! Then you wipe the product off the applicator leaving a tiny bit on and use tiny brush strokes to fill in your brow.
I use it everyday. I love it. You have to practise to start with, but once you know what's right for you, it's a 30 second job and it looks very natural. I take mine off every day as I don't like the thought of makeup staying on overnight but I think it stays on well if you don't.